Fake walnuts filled with cement being sold in China (VIDEO)

China's got a new nut phenomenon on its hands: Fraudsters are reportedly passing off walnut shells filled with cement as the fresh variety of the population's favorite snack.

According to Business Insider, shells are emptied of the actual nut, filled with concrete and paper, and then glued shut. Scammers have almost doubled their profit with this ruse, selling both the nutmeat and the fake nut.

One man in Zhengzhou city who bought 2.5kg of walnuts from a street vendor last year was taken by the scam, only realizing he had been tricked when he cracked one open and saw that it was full of concrete chips.

Counterfeiting is a massive industry in China, with a surge of fake food taking over the market in recent years, reported the International Business Times. Six babies died in 2008 and thousands were admitted to hospitals after drinking milk formula laced with melamine, a component of plastics.

Fake walnuts have become so common in China — possibly because of their jump in price, from 350 yuan 10 years ago, to as much as 30,000 yuan last year — that videos have been circling online instructing consumers how to tell if their shells are full of cement. So if you're worried about your next nut purchase, make sure to follow the tips below: